Messages in this thread | | | Date | Thu, 18 Nov 2010 16:37:34 -0500 | From | Mark Lord <> | Subject | Re: [PATCH 1/2] fs: Do not dispatch FITRIM through separate super_operation |
| |
On 10-11-18 12:19 PM, James Bottomley wrote: > > Not stepping into the debate: I'm happy to see punch go to the mapping > data and FITRIM pick it up later. > > However, I think it's time to question whether we actually still want to > allow online discard at all. Most of the benchmarks show it to be a net > lose to almost everything (either SSD or Thinly Provisioned arrays), so > it's become an "enable this to degrade performance" option with no > upside.
I also suspect that online TRIM exerts significant premature wear on the SSDs. TRIM operations most likely trigger immediate copy/erase operations internal to most SSDs, often regardless of the amount of data being trimmed.
Performing a 256KB erase because of a 1024-byte TRIM, over and over, is going to harm the expected lifetime of an SSD. Sure, some SSDs may do things differently internally, but I don't see it working that way in much of the current crop of SSDs.
Currently, I patch my kernels to remove the automatic online TRIMs. Is there a knob somewhere for this in the later kernels?
Cheers
| |